Process for butadiene polymerization using zirconocene or titanocene and lithium hydrocarbon reaction product as catalyst



United States Patent PROCESS FOR BUTADIENE POLYMERIZATION USINGZIRCONOCENE 0R TITANOCENE AND LITHIUM HYDROCARBON REACTION PROD- UCT ASCATALYST Adel F. Halasa and George E. P. Smith, Jr., Akron,

Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio, acorporation of Ohio No Drawing. Filed Feb. 1, 1966, Ser. No. 523,906

Int. Cl. C08d 1/14, 1/32 US. Cl. 260--94.3 6 Claims ABSTRACT OF THEDISCLOSURE Conjugated diolefins or mixtures thereof with otherethylenically unsaturated compounds copolymerizable therewith, arepolymerized in the presence of catalytic compounds of the formula (Ti UZr)=hal2 I I I (hydrocarbon) wherein the cyclic structures arecyclopentadiene nuclei, it being understood that the carbon atoms in therings carry hydrogen atoms unless they are' attached to hydrocarbonradicals or to the titanium or zirconium atoms;

Hydrocarbon indicates the attachment of up to 3 hydrocarbon groups tothe cyclopentadiene ring, each hydrocarbon group containing from 1 tocarbon atoms. It will be understood a bridging hydrocarbon chain maytake the place of two of the hydrocarbon groups, as in the indenenucleus;

the titanium or zirconium atom is attached to one of the carbons in eachof the cyclopentadiene rings;

hal indicates the attachment of two halogen atoms to the titanium orzirconium atoms. The halogen atoms, independently in each occurrence,may be chlorine, bromine or iodine;

(Ti U Zr) indicates an atom selected from the group consisting oftitanium and zirconium;

m is an integer from 0 to 3;

n is an integer from 1 to (8-m);

The resultant polymers are characterized by excellent green strength andbuilding tack, and by desirable underlying fundamental properties, viz,broad molecular weight distribution, high cis-l,4 structure, anddesirable microgel content.

This invention relates to the polymerization of conjugated diolefins.

In recent years there have been developed processes for thepolymerization of conjugated diolefins using catalysts based uponlithium, i.e., lithium metal or compounds of lithium in which thelithium is sufiiciently active to displace hydrogen from water, e.g.hydrocarbon lithium and the like. These catalysts produce polymers whichare high in the desirable cis-1,4 structure, and which yield excellentrubbery vulcanizates. However, particularly where it is desired toobtain the highest possible cis-1,4 structure, the catalysts must beemployed in extremely small quantities, which leads to difiiculties ofc0ntrol, since greater or lesser amounts of the unavoidably variabletrace impurities in the monomers, solvent and other components of thesystem will produce a disproportionate disturbance in a low-catalystsystem. Likewise the polymers leave something to be desired in greenstrength. In unvulcanized state, these polymers tend to lack themechanical strength requisite for processing and fabricating operationsnecessarily carried out thereon prior to vulcanization. Typically, themaximum stress which the unvulcanized materials will exhibit duringdeformation is rather low, occurs at an early stage in the deformation,and, moreover, drops off quite rapidly as the deformation continuesbeyond the point at which maximum stress is exhibited. Unvulcanizedstrip or other preforms are apt to pull apart taffy-wise during buildingetc. operations carried out thereon.

Another characteristic in which these polymers leave something to bedesired is the matter of building tack. In the construction of tires andother manufactured articles, it is frequently necessary to assemblecomponents of uncured rubbery material together, making use of theirnatural autoadhesion or building tack.

The deficiencies of these polymers discussed above appear to beconnected in some way with the narrow molecular weight range and absenceof microgel (gel particles small enough so as not to interfere with theprocessability of the polymers) characteristic of these polymers.

Accordingly it is an object of this invention to provide a novel andimproved process for the polymerization of conjugated diolefins makinguse of lithium catalysis.

Another object is to provide such a process which is readily andreproducibly controllable.

A further object is to provide such a process which will result inpolymers having desirable green strength characteristics.

A further object is to provide such a process which 'will result inpolymers having good building tack.

A still further object is to provide such a process which will producepolymers having a Wider molecular weight distribution, and an enhancedmicrogel, as compared with polymers of this type heretofore produced.

SYNOPSIS OF THE INVENTION The above and other objects are secured, inaccordance with this invention, by polymerizing conjugated diolefins, ormixtures thereof with other olefinically unsaturated compoundscopolymerizable therewith, in the presence of a catalyst comprising thereaction product of a lithium hydrocarbon compound with a titanocene orzirconocene dihalide in molar ratios of carbon-bound lithium: titanoceneor zirconocene dihalide in the range of 1:1 to 10:1. The process is muchless disturbed by impurities in the polymerization system, than has beenthe case with hydrocarbon lithium and other lithium-based catalystsheretofore employed. The polymeric products are characterized byexcellent green strength and building tack, and by desirable fundamentalproperties, viz. broad molecular weight distribution, high cis-1,4structure, and desirable microgel content, as well as excellentvulcanizate properties after vulcanization by sulfur/accelerators withany of the known vulcanization systems.

THE MONOMERS TO BE POLYMERIZED These may be any of the conjugateddiolefins containing up to six carbon atoms, or mixtures thereof witheach other or with lesser proportions (say up to 30%, based on the totalweight of monomers) of other unsaturated compounds copolymerizabletherewith. Examples of suitable conjugated diolefins include, forinstance butadiene, isoprene, 2,3-dimethyl butadiene, piperylene,1,2-dimethyl butadiene, and the like. Other monomers which may becopolymerized with the conjugated diolefins include the vinylsubstituted 'benzenes such as styrene, alpha-methyl styrene, pandm-methyl and ethyl-substituted sty renes, allene, vinyl naphthalene,acrylonitrile, methacrylonitrile, acrylate esters, methacrylate esters,amides, etc. and the like.

These should be used in minor amounts, say not more than 30%, based onthe total weight of the conjugated diolefins and comonomers, so as toleave intact the essential polydiolefin character of the polymericproducts.

THE LITHIUM HYDROCARBON-TITANOCENE OR ZIRCONOCENE DIHALIDE PRODUCTSThese may be prepared by reacting together, in a suitable inert organicmedium, a hydrocarbon lithium compound with a titanocene or zirconocenedihalide, or a hydrocarbon-substituted compound of this type, in moleratios of carbon-bound lithium: titanocene or zirconocene dihalide of1:1 to about :1 and preferably 2:1 to 8:1. Suitable compounds will ingeneral be those answering the formula Hydrocarbonn-a 1 Ti or Z 1 119.12

| l HYdI'OCfllbOnu-aU the cyclic structures are cyclopentadiene nuclei,it being understood that the carbon atoms in the rings carry hydrogenatoms unless they are attached to hydrocarbon radicals or to thetitanium or zirconium atoms;

Hydrocarbon indicates the attachment of up to 3 hydrocarbon groups tothe cyclopentadiene ring, each hydrocarbon group containing from 1 to 10carbon atoms. It will be understood a bridging hydrocarbon chain maytake the place of two of the hydrocarbon groups as irr the indenenucleus;

The titanium or zirconium atom is attached to one of the carbons in eachof the cyclopentadiene rings;

hal indicates the attachment of two halogen atoms to the titanium orzirconium atom. The halogen atoms, independently in each occurrence, maybe chlorine, bromine or iodine.

Suitable compounds include for instance titanocene dichloride,titanocene dibromide, titanocene chloroiodide, zirconocene dichloride,zirconocene diiodide, and hydrocarbon-substituted compounds of this typesuch as methyl titanocene dichloride, ethyl titanocene dichloride,methyl zirconocene dichloride, dipropyl titanocene dichloride, octyltitanocene dibromide, methyl ethyl titanocene dichloride, trioctyltitanocene dichloride, hexamethyl titanocene dichloride, hexamethylzirconocene dichloride, and bridged ring homologs of these compoundssuch as the indene ring-containing compound having the formula whereinand the like. Suitable hydrocarbon lithium compounds include, forinstance, any hydrocarbons containing up to 40 carbon atoms in which oneor more hydrogen atoms have been replaced by lithium atoms, such asethyl lithium, butyl lithium, dodecyl lithium, tetramethylene dilithium,pentamethylene dilithium, phenyl lithium, benzyl lithium, and the like.The reaction has not been fully elucidated, but it appears that thelithium in the hydrocarbon lithium compound replaces one or morehydrogen atoms of the titanocene or zirconocene, the hydrogen sodisplaced combining with the hydrocarbon radical of the lithium compoundto form the free hydrocarbon. The reaction may be written thus, for thereplacement of a single hydrogen atom by the action of butyl lithium:

C(HQLl -i- H Li -P u u The equation is written for unsubstitutedtitanocene and zirconocene compounds, but would also be applicable tothe substituted compounds, mutatis mutandis. It will be understood thatmore than one hydrogen of the compound may be replaced in this way, upto a total of about four hydrogen atoms per ring or eight hydrogen atomsfor the entire molecule.

The unsubstituted titanocene or zirconocene halide molecule contains tenhydrogen atoms, of which eight may be replaced by lithium. Assuming thatm, an integer from 0 to 3, is the number of hydrogens that have beenreplaced by hydrocarbon groups, the 8m=n will be the maximum number oflithium atoms in the final reaction product. On this basis, the formulaof the reaction prodare cyclopentadiene nuclei, it being understood thatthe carbon atoms in the rings carry hydrogen atoms unless they areattached to hydrocarbon radicals or to the titanium or zirconium atoms.

Hydrocarbon indicates the attachment of up to 3 hydrocarbon groups tothe cyclopentadiene rings, each hydrocarbon group containing from 1 to10 carbon atoms. It will be understood a bridging hydrocarbon chain maytake the place of two of the hydrocarbon groups, as in the indenenucleus.

half indicates the attachment of two halogen atoms to the titanium orzirconium atom. The halogen atoms, independently in each occurrence, maybe chlorine, bromine or iodine.

(Ti U Zr) indicates an atom selected from the group consisting oftitanium and zirconium, and attached to one of the carbons in each ofthe cyclopentadiene rings.

m is an integer from to 3 n is an integer from 1 to (8m) The reactionproduct takes the form of a precipitate which settles out of thereaction mass. Generally, the reaction is carried out at temperatures inthe range of to 100 C. As noted above, the reaction is carried out in aninert organic solvent, usually in an amount such that the titanocene orzirconocene will constitute from .00'1% to 75% of the sum of the weightsof the solvent and titanocene or zirconocene. Suitable inert organicsolvents are exemplified in hydrocarbons containing up to 40 carbonatoms, or preferably up to 16 carbon atoms such as paraffins on theorder of propane, butane, hexane, cyclohexane, methyl cyclohexane,heptane, petroleum ether, kerosene, diesel oil or the like, or aromatichydrocarbons such as benzene, toluene, the several xylenes, hydrogenatedaromatics such as tetralin, decalin, and the like.

THE POLYMERIZATION PROCEDURE The polymerization may be carried out inbulk, in the absence of any solvent, or in solution in a solvent such assuggested above for the preparation of the catalyst. Usually, sufiicientpressure is applied to keep the greater part of the conjugated diolefinin the liquid phase, although the polymerization may be carried out withthe conjugated diolefin in the gaseous phase. The polymerization iscarried out by contacting the monomeric material, i.e. the diolefins ormixtures thereof together with any monomers to be copolymerized therein,either in bulk or in solution in a solvent, with the catalyst preparedas described above, at temperatures on the order of 20 C. to +150 C.,preferably C. to +85 C.

As to the amount of catalyst to be used, in general, the larger theamount of catalyst used, the more rapidly the polymerization willproceed. Countervailing this desirable effect, high concentrations ofcatalysts tend to lower the molecular weight of the polymers and alsoalter the microstructure of the polymeric chains. Based on theseconsiderations, the amount of catalyst employed should be such as tocontain no more than 0.1 gram, and preferably not more than 0.02 gram,of carbon-linked lithium, expressed as metallic lithium, per 100 gramsof isoprene in the polymerization mixture. There appears to be notheoretical lower limit to the amount of catalyst used; at lowconcentrations, the catalysts appear to have a high order of efiiciency,i.e., if the reaction environment is scrupulously purged of allcontaminants such as oxygen, ozone, water, carbon dioxide, etc., whichwould react with and consume the catalyst, the catalyst appears to beused principally in the production of polymer chains so that, as long asany catalyst is present, some degree of polymerization will take place.For economic reasons of obtaining a rapid reaction rate and optimumreactor utilization, it is preferred to have at least 0.00002 gram ofcarbonbonded lithium present per 100 grams, of isoprene. The aboveconcentrations are, of course, expressed on the basis of catalysteffectively present in the polymerization mass; it substances which willreact with and destroy the catalyst are permitted to enter the reactionzone, the amount of catalyst so destroyed must be subtracted from thatsupplied in applying the above criteria.

For the purpose of establishing the effective concentration ofcarbon-linked lithium in any catalyst preparation employed in thepractice of this invention, the differential titration technique ofGilman and Haubein, I. Am. Chem. Soc. 66; 1515 (1944), has been foundthe most suitable procedure, and the concentrations referred tohereinabove and in the claims are to be applied on the basis of analysesmade by this method, if any question arises on this point. For mostpractical purposes, where side reactions are not suspected, simpletitration with acid will give reasonably accurate results.

The monomeric material may be dissolved in any of the solvents mentionedabove as suitable vehicles for the preparation ofthe catalyst itself.The concentration of monomers is most conveniently kept in the range of3% to 15% by weight of the entire polymerization mass, as the materialsare most readily handled in this range. However, this is not critical,and higher or lower concentrations may be employed. The systempreferably should be kept free as possible from oxygen and/or oxygenatedor nitrogenous compounds such as water, ethers, ketones, esters, aminesand the like, as these compounds tend to react with and destroy thecatalyst, and if present in amounts in excess stoichiometrically inrelation to the catalyst, will increasingly diminish the cis-1,4configuration of the polymeric products. The polymerization should becarried out in such a manner as to insure thorough contact of thecatalyst and monomers, and elfective removal of heat; for instance, withsmall scale operations, in glass bottles which are tumbled, at leastinitially, to effect mixing; or on a large scale, in autoclaves providedwith rotary agitators and cooling jackets. After the polymerization hasproceeded to the desired extent, the polymer may be recovered from thesolution by any suitable means, for instance by injection into hotwater, which will flash off the solvent or any unreacted monomers,leaving the polymer as crumbs dispersed in the 'water; or by drying on adrum or extruder dryer; or by mixing the solution with a non-solvent forthe polymer, such as methanol, isopropyl alcohol or the like toprecipitate the polymer.

One of the advantages of the present invention is its lesser sensitivityto variations in catalyst concentration, and to impurities in thesystem. In order to secure optimum polymer structure and desirablemolecular weight, it is necessary, with the simple hydrocarbon lithiumcatalysts, to employ these in very low concentrations, at whichconcentrations small amounts of impurities exert a disproportionatedestructive and/or modifying action thereon. The present catalysts maybe used in larger amounts to achieve the same excellent polymerproperties and are, moreover, less sensitive to impurities; and a lessscrupulous control and monitoring of catalyst concentrations in relationto monomer and solvent impurities may be observed without undulyaffecting the process and product.

THE POLYMERIC PRODUCTS The products of the process of the invention arecharacterized by high and reproducible molecular weight, and excellentmicrostructure, in optimum cases having cis-1,4 contents, as reflectedby infra-red measurements, on the order of 94.0+%. Moreover the productsappear to be characterized by lesser amounts of unidentifiablestructures, as reflected by higher values for total found figuresobtained on such measurements. The products also appear to have a widerdispersion of molecular weights, as compared to polymers hithertoprepared from lithium-based catalysts. These dilferences in fundamentalstructure are reflected in the improved technical properties of theproducts of this invention. Earlier polymers have been somewhatdeficient in building tack, i.e., self-adhesiveness in the unvulcanizedstate which enables plies of the polymers to be built upv into uncuredpreforms; and in green strengt -upon deformation of the unvulcanizedmaterials, the stress increases up to a certain point, the maximumstress, at a rather early point in the deformation, and thereafterdecays rapidly upon further deformation. The polymers produced in accordance with the present invention have much improved tack, and exhibita much improved unvulcanized green strength, in comparison with previouslithium polymers.

EVALUATION OF THE POLYMERS 1 1+ z z+ s a+ a s where D =absorbance(optical density) of the polymer at wavelength i,

e ,=the absorptivities of the severai structures at wavelength i, thesubscripts 1,2,3 or 4 referring to the several component structures, and

C or C =the concentrations of the several structures,

the subscripts 1, 2, 3 or 4 referring to the several componentstructures.

The four equations obtained in this way were solved for C C C and C thevalues of the concentrations of the cis-1,4-, trans-1,4-; 1,2-additionand 3,4-addition of the polymer.

The peak wavelengths selected, and the values of the absorptivities efor these Wavelengths for the several structures, are tabulatedherewith:

Molar absorptivities e at wavelength ot- Structure, microns 8. 6 8.8510. 98 11. 25 1,2addition- 3. 3. 0 149. 0 9. 0 3,4-additior1. 1. 2. 0 7.0 145. 0 Cis-lA-addition 3. 583 6. 518 l. 860 1. 530 Trans-1,4-addition5. 927 1. 9-.4 2. 277 1. 885

In the detailed examples given hereinafter, percentage values are givenfor the various types of unsaturation. These are derived by dividing theabsolute concentration of each type of unsaturation by the sum of theconcentrations of the four types of unsaturation (1,2-; 3,4-; cisandtrans-) determined, and multiplying by 100%, so that the sum of thepercentages given will always be 100%. In order to assess the accuracyof the determination, a further figure is given, narnely totalunsaturation found, hereinafter abbreviated T.F. This is the quotient orthe sum of the concentrations of the various types of unsaturation foundby infra-red analysis, divided by the theoretical concentration of allunsaturation which should be present in the sample, assuming, forexample, that the polyisoprene is constituted solely of CH;(CH2('J=CHCH2-) units.

Gel and dilute solution viscosity were also determined as follows.

DETERMINATION OF GEL AND DILUTE SOLU- TION VISCOSITY (HEREINAFTERABBREVI- ATED DSV) ON PC-LYBUTADIENE AND POLY- ISOPRENE POLYMERSApparatus (a) 125 m1. flasks (b) GP or redistilled toluene (c) 5, 10, 25and 50 ml. pipettes and 100 ml. graduates (d) 100 mesh, conical, steelscreens, aluminum cups, and

Reeve Angel filter paper, No. 802

(e) Constant temperature bath equipped with a thermometer reading totenths of a degree and a stirrer (f) A timer reading to tenths of asecond (g) No. 50 Ostwald viscometer Procedure (a) If the dilutesolution viscosity is thought to be around 6.0-7.0 or lower, accuratelyweigh 0.4000 g. polymer. If the dilute solution viscosity is thought tobe 6.0- 7.0 or higher, accurately weigh 0.2000 g. polymer. The polymershould be unmilled and finely cut. Place the sample in a 125mlfErlenmeyer flask and cover with exactly ml. C.P. or redistilledtolnene which contains 0.0075 g. phenyl betanaphthylamine per liter.Swirl gently to separate the particles.

(b) Set the flask in a dark place. Several hours later swirl again toremove polymer from the bottom of the flask. Twenty-four hours latershake again making sure all the polymer is removed from the bottom ofthe flask. A neoprene policeman may be necessary to accomplish this.Take care that no polymer remains on the policeman. Allow to stand forabout an hour.

(0) Filter the liquid through a screen and/ or the filter paperdepending upon the gel present. Weigh an aluminum cup.

(d) Pipette a 10 ml. aliquot of the filtered solution into the aluminumcup and evaporate to dryness on a hot plate at 100 C.- C. Place in a hotair oven at 100 C. for an hour. Cool for a few minutes and weigh. Thisweight will be needed to calculate gel content and dilute solutionviscosity.

(e) For dilute solution viscosity, adjust the constant temperature bathto 25 C.:0.1 C.

(f) Rinse a clean No. 50 Ostwald viscometer two or three times with C.P.or redistilled toluene to which has been added 0.0075 g. phenyibeta-naphthylamine per liter. Drain the viscometer as dry as possiblewithout the use of a vacuum line and place in the constant temperaturebath. Pipette 5 ml. of toluene plus phenyl beta-naphthylamine into thelarge arm of the Ostwald viscometer.

(g) Draw the solvent above the second blue mark on the smaii arm of theviscometer. Measure the time it takes the solvent to flow between thetwo marks on the viscometer. The flow time of two runs should checkwithin 0.2

sec.

(h) Dilute the polymer solution to a concentration so that the ratio ofthe flow time of the polymer solution to the flow time of the solvent isbetween 1.1 and 1.5. In high molecular weight polymers the concentrationmay have to be as low as 0.0150 g./100 ml. The concentration of thesolution in grams/ i00 ml. is necessary in the final calculation ofdilute solution viscosity.

(i) Pipette about 5 ml. of the polymer solution into the large arm ofthe viscometer. Draw the solution up through the capillary to rinse outthe solvent. Drain the viscometer. Pipette 5 ml. of the polymer solutioninto the viscometer and measure the flow time as described above.

INFORMATION NEEDED FOR CALCULATION OF GEL AND DILUTE SOLUTION VISCOSITY(1) Weight of sample (0.2000 g. or 0.4000 g.)

(2) Weight of aluminum cup (3) Weight of aluminum cup and residue of 10ml. of

aliquot of polymer solution (4) lConcentration of dilute polymersolution in g./100

(5 Flow time in seconds of the solvent (6) Flow time in seconds of thesolution CALCULATIONS INVOLVED Percent gel= Original wt. 10X

Wt. of residue of polymer solutionX 100 Original wt.

Dilute solution viscosity:

flow time in seconds of solution) X 0g (flow tlme in seconds of solvent)concentration in g./100 ml.

Values for building tack given hereinbelow were determined as follows.There was provided a cylinder two inches in diameter by two inches inlength mounted to rotate to the upper, tension-measuring, head of atensile testing machine (Instron Model TTG). The unvulcanizedcomposition to be tested was sheeted out to a thickness of V inch, andplaced on a holland cloth liner. A one-inch wide strip, together withits liner, was cutout and wrapped and secured around the cylinder,rubber side out. A similar strip was cut out and wrapped around thefirst strip, with the rubber faces in contact and a tail of the striphanging free. This tail was attached to the lower jaw of the testingmachine. The machine was then set in operation, with the lower jawretreating from the upper at a rate of two inches per minute. Themaximum tensile force, in pounds, shown on the measuring head wasrecorded as the building tack of the compound.

In addition, tensile properties of the uncured polymers were determinedby pressing and die-cutting standard tensile strips of the polymers, andpulling them in uncured state in a Scott tensile tester. The machinevalues of load, rather than the calculated stress per. unit area of thesample, were taken at the maximum value (achieved early during theelongation) and at break, and are recorded hereinafter in Tables I andII as maximum peak load and load at break. Likewise the elongation atbreak of the unvulcanized strips is recorded in their tables.

With the foregoing general discussion in mind, there are given herewithdetailed specific examples of the execution of this invention. All partsand percentages given are by weight unless otherwise indicated.

(A) PREPARATION OF LITHIUM ALKYL/TI- TANOCENE DICHLORIDE REACTIONPRODUCTS Titanocene dichloride4.95 grams (0.02 mole).

Benzene (anhydrous, freshly distilled)-60O ml.

Butyl lithium solution (1.0 molar, in heptane)l ml.

(0.10 mole).

the preparation contained .0004566 grams per ml. of carbon-boundlithium. The bottle was allowed to stand for 96 hours during which timea black precipitate continued to settle to the bottom. This precipitateconstituted the active catalyst, and it will be understood that it wasalways resuspended by agitation when samples were withdrawn for analysisor use. The preparation is designated Catalyst Preparation A inpolymerization experiments detailed herebelow.

(B) PREPARATION OF LITHIUM ALKYL/ZIR- CONOCENE DICHLORIDE REACTIONPRODUCT A series of runs was made in accordance with the above recipe,varying the amounts of isoprene solution and of catalyst from run to runas set forth hereinafter in Table I. In each run, the isoprene solutionand catalyst preparation, in the amounts selected for that run, werecharged under an argon blanket into a previously dried 28-ounce beveragebottle, which was then sealed with a nitrile rubber lined crown cap. Thebottle was then placed upon a polymerizer wheel and revolved in a bathat C. for a period of time as indicated in Table I. At the end of thistime the bottle was vented and cut open, and the polymer coagulated in amethanol bath and dried in a vacuum oven. In all cases the polymersshowed 0.0% gel content. Other particulars of the several runs are setforth herewith in Table I.

TABLE I.ALKYL LITHIUM/TITANOCENE DICHLORIDE REACTION PRODUCTPolymerization Conditions Properties of Polymer Max. F Isoprene CatalystCon- Infra-Red Analysis, Percent initial Load solution solution ver-Windup load at Elonused, used, Tune, S1011, Trans- Total tack, peak,break gation grams m1. hrs. percent C1s-1,4 1,4 1,2- 3,4- found DSV lbs.lbs. lbs. percent 200 5. 0 12 90} (Note 1) Iii 300 5. 0 12 90 93. 1 0. 00. 0 6. 9 88. 8 9. 5 300 8.0 12 90 93.2 0.0 0 0 6.8 87. 9 14. 3 400 16.0 48 90 93. 3 O. 0 0. 0 6. 6 87. 5 10. 1 400 20. 0 12 67. 2 92. 2 0. 70. 0 7. 1 83. 4 10. 6 400 20. 0 12 80. 0 91. 8 0. 7 0. 0 7. 5 84. 7 10.9 400 20. 0 12 67. 2 93. 1 0. 0 0. 0 6. 9 85. 3 11. 0 400 25. 0 12 68. 392. 2 0. 4 0. 0 7. 4 84. 4 10. 0 400 25. 0 12 66. 6 91. 5 1. 0 0. 0 7. 382. 4 l0. 9 200 13.0 48 63.0 93. 5 O. 0 0. 0 6. 5 87. 5 10. 9 200 10 1290. 0 93. 3 0. 8 0. 1 6. 7 86. 7 8. 7 200 15 12 90. 0 92. 8 0. 0 0. 0 7.2 86. 2 12. 9 200 20 48 50. 0 93. 5 0. 0 0. 1 6. 7 89. 7 9. 1 200 20 4850. 0 93. 4 0. 0 0. 0 6. 6 89. 7 9. 2 200 20 48 50. 0 93. 5 0. 0 0. 0 6.5 89. 7 9. 1

NOTE 1.Products of two runs combined as indicated by brackets.

The titanocene dichloride was dissolved in the benzene EXAM L 11 and thesolution placed in a 28-ounce beverage bottle P I in which an argonatmosphere was established and main- 0 ymenzatlon Wlth alkylhthlum/Zlrconocene tained during the subsequent operations. The contentsof the bottle were agitated and the butyl lithium solution added in 10ml. increments at intervals of 5 minutes. When all of the butyl lithiumsolution had been added, the bottle was capped with anitrile-rubber-lined crown cap provided with a perforation for thehypodermic withdrawal of the contents, and the bottle allowed to standfor 30 minutes. A sample was then withdrawn and titrated by the 'Gilman& Haubein method cited, the result indicating that dichloride reactionproduct Isoprene solution (15%, in heptane)400 grams. Butyllithium/zirconocene suspension (catalyst Preparation B prepared abovedescribed)-425 ml.

A series of polymerization runs was made in accordance with theforegoing recipe, varying the amount of catalyst preparation as setforth for the individual runs as set forth in Table II. The procedure ofExample I was Hydrocarbon indicates the attachment of up to 3hydrocarbon groups to the cyclopentadiene rings, each hydrocarbon groupcontaining from 1 to carbon atoms, and two of the hydrocarbon groupattachments selected from the group consisting of simple hydrocar- TABLEII.-ALKYL LITHIUM/ZIRCONOCENE DICHLORIDE REACTION PRODUCT Properties ofProducts Max. Infra-Red Analysis (percent) initial Load Catalyst Conver-Windup loa at Elonsolution sion, Total tack, peak, break, gation, used,ml. percent Cis-1,4 Transl,4 1,2- 3,4- found DSV lbs. lbs. lbs. percent4. 0 90 93. 8 0. 0 0. 0 6. 8 91. 9 8. 3 l6. 1 2. 8 0. 3 1, 350 5. 0 9093. 5 0. 2 0. 0 6. 3 91. 3 7. 5 14. 7 2. 8 0. 6 1, 200 6. 0 90 93. 5 0.00. 0 6. 5 89. 9 7. 2 15.4 3.0 0. 6 1, 725 8. 0 100 93. 2 0. 0 0. 0 6. 886. 4 4. 2 10. 0 3. 3 0. 3 950 10. 0 100 93. 2 0. 0 0. 0 6. 9 87. 3 4. 3ll. 6 3.2 0.3 l, 025 20. O 100 93. 1 0. 0 0. 0 6. 9 86. 4 8. 8 l2. 8 0.6 1, 050 25. 0 100 93. l 0. 0 0. 0 6. 8 86. 3 8. 6 17. 6 0.4 825 Fromthe foregoing general discussion and detailed specific experimentalexamples, it will be seen that this invention provides a novel processfor the polymerization of conjugated diolefins to yield products ofimproved microstructure and physical properties, particularly greenstrength and tack. The process is more readily controllable andreproducible than earlier processes based upon lithium compoundcatalysts, and the reactants employed are inexpensive and readilyavailable.

What is claimed is:

1. Process of producing a polymeric product having excellent greenstrength and building tack, broad molecular Weight distribution, highcis-1,4 structure and desirable microgel content which comprisespolymerizing conjugated diolefins containing up to six carbon atoms, ormixtures of such conjugated diolefins with each other and with up to30%, based on the weight of such mixtures, or other unsaturatedcompounds copolymerizable therewith, which comprises contacting the samewith a catalyst comprising a compound of the formula (hydrocarbon)m arecyclopentadiene nuclei,

bon groups and hydrocarbon groups bridging across the two points ofattachment,

(Ti U Zr) indicates an atom selected from the group consisting oftitanium and zirconium and attached to one of the carbons in each of thecyclopentadiene rings,

hal indicates the attachment to the atom indicated by (Ti U Zr) of twohalogen atoms selected, independently in each occurrence, from the groupconsisting of chlorine, bromine and iodine mis an integer from 0 to 3 nis an integer from 1 to (8-m).

2. Process according to claim 1, wherein the conjugated diolefin isisoprene.

3. Process according to claim 1 wherein (TiU Zr) is titanium, and halrepresents two chlorine atoms.

4. Process according to claim 1 wherein (TiU Zr) is zirconium and halrepresents two chlorine atoms.

5. Process according to claim 2, wherein n is greater than 2.

6. Process according to claim 1, wherein the conjugated diolefin isbutadiene.

References Cited UNITED STATES PATENTS 3,028,406 4/1962 Brantley 2604392,924,593 2/1960 Breslow 260-949 FOREIGN PATENTS 1,061,323 9/1959Germany.

JOSEPH L. SCHOFER, Primary Examiner R. A. GAITI-IER, Assistant ExaminerU.S. Cl. X.R.

